床の上には座ってはいけない。

bed; bedding; sickbed; alcove; riverbed; seedbed; straw "core" of a tatami mat; floor

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

to sit; to squat; to assume (a position); to hold steady; to hold still

if ... then; when; and; why don't you...?; the more (one does something); because; since